I. COMPARATIVE TASTE STUDY ON NILE TILAPIA (Oreochromis niloticus) AND MARINE FISH IN SAMOA.
PART I: with Deep Bottom Fish and Skipjack

LUI A.J. BELL¹, ANTONIO P. MULIPOLA¹ and YOSHINOBU MATSUNAGA²

Abstract

- This study examined the acceptability of the Nile tilapia as a food fish by having the public evaluating its taste against those of other fish cooked in the same way. For this study, Nile tilapia was cooked in different traditional methods: boiled in coconut cream, baked in the Samoan “umu” and smoked. The first two methods are common ways of cooking fish traditionally in Samoa. In addition, skipjack and bottomfish were also smoked the same way Nile tilapia was smoked. No other fish, except tilapia, was cooked in coconut cream but tasters were asked to compare its taste with other fish, such as reef fish. The results for tilapia cooked in coconut cream indicated that 62% of the respondents preferred Nile tilapia over other fish while the other 38% rated tilapia to be the same as other fish. For fish that was cooked in the Samoan “Umu”, 61% of the respondents preferred tilapia over bottomfish (snappers), 33% rated both tilapia and bottomfish the same and only 6% preferred bottomfish over tilapia. The results obtained for fish that were marinated with garlic and curry and then smoked were that 64% of the responses rated bottomfish as their first preference, 30% rated tilapia as their first preference and only 6% rated skipjack as their first preference. For fish that were marinated in soy sauce and ginger and then smoked, about 48% of the respondents rated bottomfish as the first preference, about 46% rated tilapia, as their first preference and only about 6% preferred skipjack over the other two.

1. Introduction

Rural communities in Samoa continue to rely heavily on the nearby reefs and lagoons for their supply of protein. The change from a barter to a cash-based economy has increased utilisation of the limited natural resources. This has resulted in increased fishing effort and the use of destructive fishing methods. Fishery resource landings from the shallow-water reefs and lagoons have been decreasing with some of the fisheries facing the threat of disappearing altogether. In an effort to divert fishing pressures from the limited and over-exploited inshore resources, government has initiated programmes aimed at providing an alternative source, not only of protein, but also a means of generating income. Aquaculture, particularly inland-water fish farming, is considered to offer one of the potential alternatives.

Fisheries Division, with assistance from the South Pacific Aquaculture Development Project Phase II (SPADP), has initiated the Nile tilapia farming in Samoa. However, in order to assess the possibility of expanding fish farming into the village level, it was seen necessary to conduct an assessment of the general acceptance of the target species, O. niloticus, by the rural communities and the public. This assessment was also seen as an appropriate measure of the likeness of this development to effectively divert fishing from reefs and lagoons.

Mozambique tilapia (Oreochromis mossambicus) was introduced into Samoa around 1955–1960. Natural ponds and streams were stocked. At present, tilapia forms a subsistence fishery in a few villages on a very low level. However, tilapia is also utilised on the artisanal level in at least one village on Savaii.

The initiation of a Fisheries Division Open Day, 2 November 1995 was seen as an excellent opportunity to conduct a taste assessment on the acceptability of the Nile tilapia by the general public.

¹ Fisheries Division, Apia
² United Nations Volunteer

2. Materials and Methods

In order to get a proper evaluation of the people's reaction to eating tilapia, it was decided that it should be assessed against fish of high value in Samoa. In addition, it was believed that the reaction to the more commonly used way of cooking fish traditionally, would give a better assessment on the acceptance of Nile tilapia by the local population.

Tilapia was purchased at the Naduruloulou Aquaculture Station in Fiji. Before shipping to Samoa, the tilapia was kept in the raceway tanks without feeding for 2 days. Approximately 100kg of gutted and gill-out fresh Nile tilapia, approximately 300g per fish, were shipped, on ice, from Fiji by SPADP the day before cooking on the Fisheries Open Day. They were all well kept on ice in a cooler until they were used.

2.1 Fish Cooked in Coconut Cream

One of the most common ways of cooking fish in Samoa is by boiling in coconut cream. This merely involves preparing the fish by taking out the viscera and sometimes scales are removed. The fish are then washed and placed in the cooking pot. Freshly squeezed out coconut cream is then added together with salt and onions. Water is added if the cream is too thick and that all fish must be completely submerged in the cream mixture. It is then boiled over the fire.

The Nile tilapia samples used for the taste test were prepared in the same way as described above except the scales were not removed. Only Nile tilapia were prepared this way.

The cooked tilapia were placed on a plate from which people sampled. People were asked to evaluate it against other fish such as reef fish.

2.2 Fish Cooked in a Samoan “Umu”

Cooking fish in the “umu” is the other most common method of cooking fish in Samoa. The “umu” is the Samoan method of baking food using hot stones covered with leaves. It is the equivalent of the Fijian “lovo”.

Tilapia and bottomfish (snappers: Pristipomoides) specimens were wrapped separately in breadfruit leaves. Prior to wrapping, however, Nile tilapia were soaked in brine for 7 minutes. Three to four individual fish were included in one wrapping. These were then cooked in the “umu”.

The umu-cooked tilapia and bottomfish were displayed side by side on a table and tasting was done one right after the other. People who sampled these were asked to indicate which fish was better tasting.

2.3 Smoked Fish

The inclusion of smoked fish in this assessment was to evaluate tilapia against other fishes but particularly, because smoked fish is part of the Fisheries Division efforts to promote “value-added” processing of fish.

Nile tilapia, bottomfish and skipjack specimens used for smoking were brined in vinegar and treated with two different flavours. One lot of Nile tilapia, bottomfish and skipjack was marinated with garlic and curry and a different lot was marinated with soy sauce and ginger. All samples were smoked using the same wood. Assessment for the fish smoked with different flavours were conducted separately. The cooked fish were displayed side by side on a table and tasting was done one after the other.

3. Results

3.1 Fish Cooked in Coconut Cream

Table 1a records the results of the assessment conducted for Nile tilapia cooked in coconut cream. A total of 37 people (24 males, 12 females, 1 unrecorded) sampled Nile tilapia cooked in coconut cream.

Table 1a. Results of comparative taste survey on Nile tilapia and reef fish cooked in coconut cream with salt and onions

NR - Not recorded
FETP - Fisheries Extension and Training Project

There was no other fish (reef or bottomfish) cooked the same way on the day of the assessment. However, the tasters were asked to compare the taste of this “fish” with other fish, such as reef fish, cooked in the same way. It was not made known to the tasters that the fish was tilapia prior to them giving their assessment. The results indicated that of the thirty-seven responses, 23 (62%) rated Nile tilapia cooked in coconut cream as better than other other fish cooked the same way. Fourteen (38%) of the responses rated Nile tilapia to be the same as other fish and no one indicated that tilapia cooked this way was worse than other fish. Twelve (33%) of the 36 tasters (with recorded sex) were females. Seven (58%) of 12 female respondents valued tilapia better. However, of the 24 male respondents (67%) valued tilapia better.

Table 1b records the responses by age groups, 6–15, 16–25, 26–35 and 35+ years of age. The 6–15 age group was poorly represented, whereas the other three groups, excluding those with ages not given, were fairly closely represented in terms of numbers. Using percentages only, the majority (67%) of the youngest age group (6–15 years, represented by only 3 individuals) indicated that tilapia cooked in coconut cream tasted the same as other fish, such as reef fish. The majority (58%) of the oldest age group (36+ years, consisting of 12 individuals) indicated that tilapia cooked in coconut cream tasted better than other fish. However, 42% of the respondents of that age group indicated that tilapia cooked in coconut cream was the same as other fish. For the middle age group (16–25 and 26–35 years), the vast majority (70 and 78% respectively) indicated preference on tilapia cooked this way over other fish, including reef fish. Three respondents did not give their ages. Nevertheless, 2 of these rated tilapia as tasting the same as other fish while one rated tilapia as better.

Table 1b. Results of comparative taste survey sorted by age group on Nile tilapia and reef fish cooked in coconut cream

3.2 Fish cooked in a Samoan “Umu”

A total of 33 people participated in the comparative taste assessment of Nile tilapia and bottomfish cooked in a Samoan “umu”. The results are recorded in Table 2 which indicates that of the total 33 people involved, 22 were males and 11 were females. The combined results for this method of cooking show that of the total 33 respondents, 20 people (61%) preferred tilapia over bottomfish. Eleven (33%) indicated that Nile tilapia and bottomfish tasted the same and only 2 (6%) indicated bottomfish as better than Nile tilapia.

The responses were separated by sex, and of the 11 females that participated, 6 (55%) indicated that the Nile tilapia and bottomfish cooked this way tasted the same. Four (36%) preferred Nile tilapia over bottomfish while only one (9%) preferred bottomfish over Nile tilapia. For the 22 male participants, 16 (73%) preferred the Nile tilapia over bottomfish. Five (23%) indicated that tilapia and bottomfish tasted the same while only 1 (5%) preferred bottomfish over tilapia.

Table 2a. Results of comparative taste survey results on Nile tilapia and bottomfish wrapped in breadfruit leaves and cooked in Samoan “umu”

NR - Not recorded

Table 2b records details pertaining to results broken down to age groups, as used above. All of the age groups were fairly close in terms of numbers even though representatives of each group were small. The age groups 6–15 and 16–25 had the same number of tasters (7) and both had four (57%) indicating tilapia as the better fish. However, the 16–25 age group had one (14%) indicating bottomfish as the better fish and two (29%) indicating the different fishes as having the same taste. No-one in the 6–15 age group said that bottomfish tasted better and that 3 (43%) said the fishes tasted the same. The marked difference is seen in the 26–35 age group where eight (89%) indicated tilapia as the better fish with the rest of the respondents (1 or 11%) indicating both fishes as having the same taste. The reverse is true of the 36+ age group. The majority of this age group (5 or 63%) indicated that bottomfish as the better tasting fish while two (25%) claimed tilapia as the better tasting fish and one (12.5%) said the fishes tasted the same.

Table 2b. Results of comparative taste survey sorted by age group, on Nile tilapia and bottomfish wrapped in breadfruit leaves and cooked in Samoan “umu”.